The Nasadiya Sukta or the Creation Hymn is the 129th Hymn from the 10th Mandala of the Rig Veda. It deals with the origin of the universe.
नासदासीन्नो सदासीत्तदानीं नासीद्रजो नो व्योमा परो यत्
किमावरीवः कुह कस्य शर्मन्नम्भः किमासीद्गहनं गभीरम् ॥१॥
न मृत्युरासीदमृतं न तर्हि न रात्र्या अह्न आसीत्प्रकेतः
आनीदवातं स्वधया तदेकं तस्माद्धान्यन्न परः किञ्चनास ॥२॥
तम आसीत्तमसा गूहळमग्रे प्रकेतं सलिलं सर्वाऽइदम्
तुच्छ्येनाभ्वपिहितं यदासीत्तपसस्तन्महिनाजायतैकम् ॥३॥
कामस्तदग्रे समवर्तताधि मनसो रेतः प्रथमं यदासीत्
सतो बन्धुमसति निरविन्दन्हृदि प्रतीष्या कवयो मनीषा ॥४॥
तिरश्चीनो विततो रश्मिरेषामधः स्विदासीदुपरि स्विदासीत्
रेतोधा आसन्महिमान आसन्त्स्वधा अवस्तात्प्रयतिः परस्तात् ॥५॥
को अद्धा वेद क इह प्र वोचत्कुत आजाता कुत इयं विसृष्टिः
अर्वाग्देवा अस्य विसर्जनेनाथा को वेद यत आबभूव ॥६॥
इयं विसृष्टिर्यत आबभूव यदि वा दधे यदि वा न
यो अस्याध्यक्षः परमे व्योमन्त्सो अङ्ग वेद यदि वा न वेद ॥७॥
Then (before the beginning) there was neither existence nor non-existence; There was no sky, nor the realm of space, or anything beyond that; What stirred? Where? In whose protection (who was responsible)?
There was neither death nor immortality then; There was no night or day; That One breathed, windless,by its own impulse; Other than that One’s breath there was nothing beyond.
When the universe began, at first, there was Darkness, hidden by darkness; There was endless water, with no distinguishing marks; The water was covered by the void; And then, The One came into being by the force of heat;
But is that what happened? Who really knows? Who here (amongst reciters) will proclaim it as true? Where did this creation happen? Do even the Gods know? The Gods came afte the creation of this universe. Who then knows whence it has arisen?
Whether the One’s will created it, or whether the One was mute; Perhaps the universe formed itself, or perhaps it did not;
Only the One, who is its overseer in highest heaven knows, Only the One knows, or perhaps even the One does not know.
The english translation above takes reference from a few different sources, as well as my basic knowledge of Sanskrit. The choice of words is mine, and may not be entirely perfect.